Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 34: Correlated Electrons: Spin Systems and Itinerant Magnets
TT 34.3: Vortrag
Freitag, 31. März 2006, 10:45–11:00, HSZ 301
Reduction of surface coverage of finite systems due to geometrical steps — •C. Olbrich1, K. Morawetz1,2, S. Gemming3, and M. Schreiber1 — 1Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany — 2Max-Planck-Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany — 3Institute of Physical Chemistry, Technical University Dresden, Germany
The coverage of surfaces interrupted by a step with molecules is simulated by a two-dimensional Ising model. An analytical mean-field model is developed which is capable to describe main properties of this frustrated Ising model due to the surface geometry. We find a reduction of coverage (magnetization) at low temperatures due to the presence of the surface step for certain bonding strengths. This represents a second transition besides the usual phase transition and is characterized by a diverging susceptibility and magnetization as a finite-size effect. The specific heat diverges with a power law due to the surface step.